Undyne

Once undyne entered the barrier room and saw all the destroyed souls she changed becoming more aggressive and she pushed the ones she loved a way to finnish her mission but when the ones you try to help attack you there's nothing you can do so undyne rushed to see if alphys was okay.

Once undyne reached the lab she accidently released the amalgams which tore through the royal guard and ravaged hotlands alphys decided not to go with undyne so she fled back to her house and locked herself away.

After afew days undyne left her home and went on a rampage eating anything that moved including her biggest fan.

One day while undyne was hunting through the sludge pits she saw her old friend thinking of him as a weak target she attacked ending his life.